Research | Children's Health .... increased respiratory symptoms, particularly in atopic children, but is not .... and FEV1 recordings made between midnight.
Research | Children’s Health Respiratory Health Effects of Exposure to Low-NOx Unflued Gas Heaters in the Classroom: A Double-Blind, Cluster-Randomized, Crossover Study Guy B. Marks,1,2,3 Wafaa Ezz,1,2 Nathan Aust,4 Brett G Toelle,1,2 Wei Xuan,1 Elena Belousova,1 Carmen Cosgrove,4 Bin Jalaludin,3 and Wayne T. Smith 2,4,5 1Woolcock
Institute of Medical Research, Sydney, New South Wales, Australia; 2University of Sydney, New South Wales, Australia; of New South Wales, Sydney, New South Wales, Australia; 4Environmental Health Branch, New South Wales Health Department, New South Wales, Australia; 5University of Newcastle, Newcastle, New South Wales, Australia 3University
Background: There are long-standing concerns about adverse effects of gas appliances on respiratory health. However, the potential adverse effect of low-NOx (nitrogen oxide) unflued gas heaters on children’s health has not been assessed. Objectives: Our goal was to compare the respiratory health effects and air quality consequences of exposure to low-NOx unflued gas heaters with exposure to non–indoor-air-emitting flued gas heaters in school classrooms. Methods: We conducted a double-blind, cluster-randomized, crossover study in 400 primary school students attending 22 schools in New South Wales, Australia. Children measured their lung function and recorded symptoms and medication use twice daily. Nitrogen dioxide (NO2) and formaldehyde concentrations were measured in classrooms using passive diffusion badges. Results: NO2 concentrations were, on average, 1.8 times higher [95% confidence interval (CI), 1.6–2.1] and formaldehyde concentrations were, on average, 9.4 ppb higher (95% CI, 5.7–13.1) during exposure to unflued gas versus flued gas heaters. Exposure to the unflued gas heaters was associated with increased cough reported in the evening [odds ratio (OR) = 1.16; 95% CI, 1.01–1.34] and wheeze reported in the morning (OR = 1.38; 95% CI, 1.04–1.83). The association with wheeze was greater in atopic subjects. There was no evidence of an adverse effect on lung function. Conclusions: We conclude that classroom exposure to low-NOx unflued gas heaters causes increased respiratory symptoms, particularly in atopic children, but is not associated with significant decrements in lung function. It is important to seek alternative sources of heating that do not have adverse effects on health. Key words: children, nitrogen dioxide, randomized controlled trial, respiratory health effects, schools. Environ Health Perspect 118:1476–1482 (2010). doi:10.1289/ehp.1002186 [Online 27 July 2010]
There has been long-standing concern about the health consequences of indoor exposure to gas combustion products (e.g., Garrett et al. 1998; Jarvis et al. 1996, 1998; Kerkhof et al. 1999; Melia et al. 1979; Ng et al. 2001; Phoa et al. 2004; Pilotto et al. 1997; Ponsonby et al. 2001a; Wong et al. 2004). Most concern has focused on the respiratory effects of emissions of oxides of nitrogen, particularly nitrogen dioxide (NO2) (Bauer et al. 1986; Chauhan et al. 2003; Tunnicliffe et al. 1994), although not all studies have demonstrated adverse effects at the observed concentrations (Salome et al. 1996; Samet et al. 1993). There have been two randomized controlled trials that contribute a higher level of evidence. One of these is a parallel-group, randomized, controlled trial of a homeheating intervention conducted in a cohort of New Zealand houses that were poorly heated, including 55% with unflued gas heaters and others with electric or other heating sources, and in which at least one child had asthma (Howden-Chapman et al. 2008). Children whose homes were insulated and fitted with an effective nonpolluting heater had less nocturnal cough and wheeze, fewer lower respiratory tract symptoms, and better self-assessed health status during winter than those in the
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control group who did not receive any intervention until the study was over. There was no difference in lung function. This study demonstrated an improvement in clinically relevant health outcomes attributable to this home modification intervention. However, it is not clear whether the change was due to the nature of the fuel source or the effectiveness of the heating. Although the active group had substantially lower NO 2 concentrations in the living room (8.5 µg/m3 vs. 15.7 µg/m3, p
